The conformation of several proteins, polypeptides and their enzyme- or cyanoen bromide-digested fragments in amphiphile solutions is studied by circular dichroism together with other physiocochemical methods. The structure-forming potential of these polymers in a hydrophobic environment provided by surfactants such as sodium dodecyl sulfate and various lipids (solubilized in a nonionic surfactant) is compared with that based on sequential-predictive method. A working hypothesis has been proposed that micelles of the amphiphiles can cluster around the peptide chain and hydrophobic interaction among the nonpolar tails of the amphiphiles stabilizes any ordered structure of the polypeptides. Such induced conformation is related to the helix- and beta-forming potentials of the amino acid sequence but it can be destabilized by charged residues of the polypeptide having the same sign as the amphiphiles.